Method of heat treating plane and unidimensional curved metallic surfaces



April 6, 1937. A. B. KINZEL 2,076,515

METHOD OF HEAT TREATING PLQNE AND UNIDIMENSIONAL CURVED METALLIC SURFACES Filed. Sept. 16, 1933 INV ENTOR Auausrus B. lf/zvza.

ATTORNEY Patented Apr. 6, 1937 UNITED STATES METHOD OF HEAT UNIDIM'ENSIONAL SURFACES TREATING PLANE AND CURVED LIETALLIC Augustus B. Kinzel, Flushing, N. Y., assignor, by mesne assignments, to Union Carbide and Carbon Corporation, a corporation of Application September 2 Claims.

This invention relates to a method of heat treating metallic objects and has more particular application to a method of hardening the surface of metallic objects by reciprocally moving a heating means relative to the object.

Heretofore it has been the practice to harden various metallic bodies, such as those made of steel and other ferrous alloys, by raising the surface temperature to the critical range and quenching in a bath orin a jet of cooling medium. Heat has been applied either by placing the body in a furnace or by directing a high temperature flame along the surface. It has also been found advantageous in heat treating curved or rounded objects, such as bearings, shafting and trunnions, to rotate them rapidly under a source of heat so as to bring the temperature uniformly to the critical range. However, in applying heat by means of an oxy-acetylene 0 blowpipe or an electric arc to the surface of bodies to be hardened, it is often impossible to employ a rotative method on account of the shape or width of the body.

An object of this invention therefore is to 25 provide an improved method of uniformly raising the temperature of relatively large metallic bodies. Another object of this invention is to provide a means for reciprocally moving a heat producing apparatus relative to the surface of a 30 metallic body which is to be case hardened. Still another object of this invention is to provide means for reciprocally and rotatively moving a high temperature producing apparatus relative to a metallic body which is subjected to heat 35 treatment. These objects and others together with the novel features of this invention will be more evident from the following description having reference to the accompanying drawing, in which-- Fig. 1 is a view in elevation of a device illustrating one embodiment of my invention and comprising a blowpipe mounted on a lathe for reciprocating movement relative to the work;

Fig. 2 is a side view of an alternative embodi- 45 ment of this invention in which the work is mounted on a carriage capable of being moved to and fro under a blowpipe; and

Fig. 3 is a plan view of another form of apparatus showing the body to be heat treated as 5 mounted on a lathe for rotative movement and a blowpipe arranged for reciprocating movement.

In accordance with this invention the surface of a metallic body B may be heat treated by setting up the body B on a support T and re- 55 ciprocally moving a blowpipe P with respect to New York 16, 1933, Serial No. 689,722 (Cl. 148-215) the surface to be hardened. The blowpipe P, as shown in Fig. 1, may be mounted on the carriage C of a lathe L ing the blowpipe back and forth over the work. A screw-cutting machine lathe has been found best suitable for this purpose, but any type of lathe may be used which has a reversible, powerdriven lead screw.

The blowpipe P and a cooling jet producing means D may be supported by a block III attached to the slide rest ll of the lathe and extend out away from the side of the lathe so as to overhang the work or body B. A number of bolts l2 serve to clamp the block i0 tightly against the slide rest H and insure cooperating lateral movement of the block I!) together with the slide rest ll across the carriage C. A crank l3 operates the slide rest II by means of a screw which is operable in the usual manner between dovetail supports M of the rest ll. 7

The lathe L- is provided with a lead screw S which cooperates with a threaded bore in an apron l5 that forms an integral part of the carriage C. Power driven means l6 which may comprise the conventional gears and a reversing mechanism (not shown) operate the lead screw S so as to move the carriage C back and forth on the shears or bed of the lathe I I and for a distance substantially equal to the length of the work B. By terminating the reciprocatory movement of the blowpipe before it reaches the ends of the work B the tendency to overheat the end edges of the work during the intervals of reversal of the blowpipe is eliminated, and the end areas are raised to the critical range of temperatures by conductance of heat from the adjacent areas.

The blowpipe P preferably comprises a head I8 having a plurality of nozzles l9 which are adapted to produce heating jets which tend to overlap and which extend across substantially the entire width or one dimension of the surface of the work to be heat treated. In this manner a high temperature heating flame of sheet-like form is produced. A sufliciently large head is employed to accommodate work of various widths, the outer nozzles which extend beyond the edges of the work being blanked oil. when they-are not required. A stem may SGIVBJZO connect the head l8 with an oxygen conduit 2| and an acetylene conduit 22 which are flexible and are connected with suitable sources of gas supply. Valves 23 and 24 may be provided to control the passage of gas through the conduits 2| and 22 respectively.

which is capable of mov- The conduit or cooling jet means D may be arranged substantially parallel to the stem 28 and be supplied with water in any suitable manner, preferably through a flexible hose 26, and the 5 flow of water controlled by a valve 26. In order to distribute the jet of water or other cooling liquid over the entire width of the heated surface. a flshtail nozzle 21 may be employed at the lower end of the conduit D to provide a sheet of cooling l0 liquid extending across one dimension of the surface heated. Both the blowpipe P and the conduit D may be passed through apertures in the block it and be secured thereto by lock nuts 28, or by other suitable means. I

To heat treat a surface of the body B the body is blocked up on the support T by shims 23 until the upper surface of the body is brought within a short distance of the nozzles i3 so that the full intensity of the blowpipe flames will impinge on the surface. The carriage C is adjusted to move back and forth substantially over the entire length of the body B, and after the blowpipe jets are ignited, the lead screw S is set in operation. As the blowpipe P moves to and fro over 25 the body B the surface is raised to the critical range of temperature, and when the critical range is reached, the gas supply may be shut oil! and the cooling medium applied to the body B by opening the valve 26. After sufficient time has elapsed for adequate cooling of the surface, the body B may be removed or re-positioned for hardening one or more of the remaining surfaces.

The critical range of temperature at which it is desired to discontinue heating and to apply the quench is determined either by the cherry red color of the surface of the work or by the length of time elapsed during which heat has been applied. The actual temperature at which quenching should take place will vary according to the quality and constituents of the metal being hardened.

An alternative embodiment of this invention, as shown in Fig. 2, may comprise an apparatus for moving the body B to be heat treated in a reciprocating manner relative to a blowpipe 3| and jet producing nozzle 32. The body B may be supported by a carriage 33 on which it is firm- 1y held by bolts 34- engaged in lugs 35, 36 on each side of the carriage. The carriage 33 may be provided with pairs of flanged wheels 31, 38 mounted on axles 33, 40 supported in bearings which are connected with the carriage, the pairs of wheels 31, 38 being operable on spaced track members ll.

The carriage 33 may be moved on the track by a power driven eccentric l2 and a connecting rod or link 43. At each end of the rod 43 pins 44 and 46 respectively serve to join the rod with the eccentric and with the carriage and to permit a swivel action when the eccentric is set in motion. The carriage operates back and forth on the rails 4| in straight line motion in accordance with the driving action of the rod. A

speed of 60 reversals per minute has beenfound to be suitable for efllcient operation although other speeds may be employed in accordance with the size or thickness of the body to be heat treated.

Both the blowpipe 3| and the nozzle 32 may be mounted on a stationary member 46 by clamps I], through which the elevation of the blowpipe and nozzle may be changed to accommodate for work of difierent size. Oxygen and acetylene gases are supplied to the blowpipe 3| by conduits I and 48, the flow therethrough being controlled by valves and 6| respectively, and

water or other cooling medium is supplied to the nozzle 32 through a quick acting valve 62. It

will be appreciated that metallic bodies may be 5 heat treated by moving the body relative to a stationary blowpipe and cooling jet nozzle in much the same manner as in the method previously described for the first form of apparatus.

Another alternative embodiment of this inven- 10 tion, as shown in Fig. 3, may comprise an arrangement of a blowpipe 6| and cooling nozzle 62 in conjunction with a lathe 63. A body B of unidimensional curvature, such as a shafting, which it is desired to case harden from end to end, 15 or over an area of appreciable length, may be suspended between the centers 34 and 66 of the head stock 66 and tail stock 61 .respectively of the lathe 63. when so held the body B may be rotated at any convenient speed while the sur- 20 face is subjected to heat from the blowpipe 6| which will raise the temperature uniformly on a peripheral area substantially equal to the width of the blowpipe.

However the surface of the body B may be 23 treated ultaneously along the entire length thereof by mounting the blowpipe 6| and nozzle 62 on the carriage 68 of the lathe and moving the carriage back and forth relative to the body by operating the lead screw 69. The blowpipe 30 6| and cooling nozzle 62 are preferably supported on a substantially horizontal plane, which intersects the center axis of the body B, by clamping these members on a block 18 which is bolted to the slide rest H of the lathe. The slide rest 35 may be moved laterally across the carriage 68 of the lathe in the usual manner so as to adjust the heating and cooling members 6| and 62 most efiectively with regard to the surface of the work. 40

When the body B and the blowpipe 6| are both moved relative to one another, one rotatively and the other reciprocally, the heating flames from the blowpipe nozzles are projected on a helical path on the surface of body B, and as the oper- 45 ation continues, the entire surface area of the body is raised to the critical range. After the correct temperature for hardening has been reached, the gases to the blowpipe may be shut off and water or cooling medium may be immeso dately supplied by the nozzle 62, which eflects rapid cooling of thebody B. The quench of the body is substantially simultaneous over the entire area, and for this reason a uniform case is produced. 56

Although more than one embodiment of this invention has been illustrated and described, it will be understood that changes may be made without departing from the scope of this invention. at

I claim:-

1. A method of hardening a surface of a metal body, portions adjacent the boundaries of said surface having a lower rate of heat loss than the remainder of said surface, such method compris- 6| ing applying a localized high temperature heating medium to said remainder of said surface while reciprocating said body and said medium relatively to one another in such a manner that the reversals of movement during such reciproca- 7 tion occur at short distances from said boundaries; repeating such reciprocation a sufllcient number of times to substantially uniformly heat said surface to or above the critical range; then discontinuing the application of said heating me- 7 diurn; and thereupon cooling such heated surface dium relatively to one another in such a manner suiiiciently to harden the same. that the reversals of movement during such re- 2. A method of hardening a unidimensional ciprocation occur at short distances from said curved surface of a metal body, portions adiaboundaries; continuing such rotation and repeat- 5 cent the boundaries of said surface having alower ing said reciprocation a sufiicient number of 5 rate of heat loss than the remainder of said surtimes to substantially uniformly heat said surface, such method comprising applying a localized face to or about the critical range; then disconhigh temperature heating medium to said retinuing the application of said heating medium; mainder of said surface while rotating said body and thereupon cooling such heated surface will- 10 about the center of curvature of said surface and ciently to harden the same. 10

also while reciprocating said body and said me- AUGUSTUS B. KINZEL. 

